1. Field of the Invention
This invention relates to a system for setting the minimum level of a gas-fired atmospheric burner, particularly for cooking hobs, ovens and like domestic appliances, the burner being associated with flow rate regulator means and flame detection and ignition devices.
2. Description of the Related Art
The minimum flame power deliverable by any gas-fired atmospheric burner is influenced by a large number of factors, resulting in the minimum flame power not being able to be correctly set by the final user if using known burners and the relative currently used flow rate regulator means (taps).
One of the factors most influencing regulation is clearly the gas pressure at the burner. This pressure can undergo daily fluctuation determined by the number of users simultaneously drawing gas from the mains for their appliances. It can also be influenced by the fact that the various users are connected to the mains at different points thereof, resulting in various pressure drops and pressure fluctuations.
Consequently to ensure that on rotating the tap into the minimum flame power position the flame remains alight under "any" operating conditions, a minimum power regulator screw is currently provided on the tap. This screw is used to preset at the manufacturing stage the minimum gas flow rate required to ensure that the flame is present when the gas pressure is the minimum prescribed by regulations. When the appliance provided with a burner preset in this manner is installed on the premises of the final user, the installer makes a fine adjustment using this screw. In this manner the minimum gas flow rate is ensured, but only under the operating conditions prevailing at the moment of this adjustment.
In the case of pressure change, a higher air percentage present in the pipes, surrounding draughts able to disturb the flame, dirt on the burner or any other influencing circumstance, the minimum flow rate preset in this manner can undergo change to the extent of resulting in extinguishing of the burner.